Method for manipulating aluminum reduction cell anode pins

ABSTRACT

METHOD AND APPARATUS FOR EXTRACTING THE ANODE PINS OF AN ELECTROLYIC REDUCTION CELL AND FOR RESETTING SUCH PINS WHILE STILL HOT. THE EQUIPMENT COMPRISES A MODIFIED FORK TRUCK HAVING, IN ADDITION TO THE CONVENTIONAL VERTICALLY MOVABLE CARRIAGE AND A REVOLVING APRON, AN EXTENSIBLE BOOM MOUNTING A PULLER-DRIVER METHANISM WHICH INCLUDES A PIN CLAMPING HEAD. MEANS ARE ALSO PROVIDED FOR REACTING THE PIN WITHDRAWAL FORCE AGAINST THE CELL STRUCTURE.

R.-J DlLL Och-24, 1972.

METHOD FOR MAMIPULATING ALUMINUM REDUCTION CELL ANODE PINS Original Filed May a. 1965 6 Sheets-Sheet 1 Q INVENTOR RAYMOND JOSEPH OILL i Q mm 0 vi x 9 9 m .o w. Z a a U 2 mm & wt U o N ATTORNEY 3,700,571 mE'r a'obFoa MANIPULATING ALUMINUM REDUCTION CELL ANODE PINS Original Fild Ma 5,-11965 6 Sh gQetS-Sheet 2 INVENTOR RAYMOND JOSEPH mu.

ATTORNEY R. J. DILL METHOD FOR MANIPULATING ALUMINUM REDUCTION CELL ANODE PINS Original File d ma a. 1965 6 Sheets-Sheet 3 INVENTOR RAYMOm JOSEPH DILL ATTORNEY METHOD FOR MANIPULATING ALUMINUM REDUCTION CELL ANODE PINS- Original Filed May 5, 1965 J. DILL 6 Sheets-Sheet 4 mvsmon RAYMOND JOSEPH OILL ATTORNEY Oct. 24', 1972 1 R. J. DlLL- I 3,700,

METHOD FOR MA-NIPULA'I'ING ALUMINUM REDUCTION 031,1, ANODE" P I'Ns Original Filed May-5.. 1965 e Sheets-Sheet 5 INVENTOR RAYMOND JOSEPH DILL ATTORNEY 0ct.24.1972 R.J. DILIL. 3,700,571

METHOD FOR MANIPULATING ALUMIIIUM REDUCTION CELL ANODE PINS Original Filer; May a. 1965 e Sheets-Sheet e INVENTOR RAYMOND JOSEPH mu.

ATTORNEY United States Patent 3,700,571 METHOD FOR MANIPULATING ALUMINUM REDUCTION CELL ANODE PINS Raymond Joseph Dill, Florence, Ala., assignor to Reynolds Metals Company, Richmond, Va.

Original application May 3, 1965, Ser. No. 452,493, now

Patent No. 3,493,486, dated Feb. 3, 1970. Divided and this application July 10, 1969, Ser. No. 862,103

Int. Cl. C22d 3/12 US. Cl. 204-67 1 Claim ABSTRACT OF THE DISCLOSURE This application is a division of prior copending application Ser. No. 452,493 (now US. Pat. 3,493,486), filed May 3, 1965.

The present invention concerns a system for manipulating anode pins or the like, such as those used to provide electrical connections to a carbon anode in an electrolytic reduction cell. More particularly, the invention relates to method and apparatus for extracting hot anode pins and resetting the pins while still hot.

Anode pins of iron or steel are conventionally employed with the carbon anodes of alumina reduction cells. In cells having Soderberg or self-baking anodes, the pins typically are arranged in rows along the side of the anode. As the carbon is consumed, the anode is lowered periodically, an eventually it becomes necessary to remove the lowermost pins in order to avoid their becoming melted and contaminating the aluminum being produced.

Prior practice has been to remove and clean the pins prior to reuse-not an easy task because, for one thing, the pins become securely anchored in the baked carbon, and they are likely to be red hot unless the cell has been shut down for some time which usually is not the case. In addition, the cleaning operation itself is troublesome, being both difiicult and time-consuming to perform.

It has been found, however, that the cleaning of such pins can be avoided altogether if they are reinserted in the carbon promptly, while still hot and before oxidation or other effects incident to cooling the pins result in formation of a strongly adherent deposit. In accordance with the invention, therefore, a principal object is to provide for handling hot anode pins, including the provision of apparatus for extracting and resetting such pins quickly and easily.

For a better understanding of the invention and its various objects, advantages and details, reference is now made to the presently preferred embodiment of the invention which is shown, for purposes of illustration only, in the accompanying drawings.

In the drawings:

FIG. 1 is a front view of the anode pin puller-driver apparatus in accordance with the invention, shown in relationship to a reduction pot;

FIG. 2 is a top view of the puller-driver apparatus shown in FIG. 1;

FIGS. 3A and 3B are enlarged elevational views, partially sectioned to show additional details of the pullerdriver mechanism seen generally in FIG. 1;

FIG. 4 is a section taken at lines 4-4 in FIG. 2;

'ice

FIGS. 5, 6 and 7 are sections taken respectively at lines 5-5, 6-6 and 7-7 in FIG. 3B; and

FIG. 8 is a schematic of the hydraulic control system.

The general arrangement of apparatus in accordance with the invention and its manner of operation are shown in FIG. 1, a front view of the modified fork truck 20 positioned alongside a reduction pot 10. The pot includes an anode 12, anode side channels 14, and several anode pins 16 passing through clearance holes in the channels to provide electrical connection between the anode and an external bus system, not shown. Conventional portions of truck 20 are the vertically movable carriage 21 and a revolving apron 22 (e.g. Model 40 of Cascade Manufacturing Company) supported on the carriage, having a rack and pinion drive (not shown) which is actuated by hydraulic cylinders 24 and 25.

Mounted on the apron 22 is a boom housing assembly 26 adapted to support an extensible boom 28. Hydraulic actuator 30 atop the housing assembly 26 has its cylinder pivotably attached to a front bracket 32 on the housing, and piston rod 34 of the actuator is attached to a rear bracket 36 which is aifixed to the outer end of the boom. At the opposite end of the boom 28 are mounted the puller-driver mechanism 42 and a support barrel 46, the construction and operation of which are hereinafter described.

FIG. 4 provides a transverse section through the boom housing assembly 26, showing the arrangement by which the boom 28 is mounted for reciprocating movement within the housing. Upper and lower rollers 50 having integral flanges 52 afiord support and guidance for the boom, and suitable bearings 54 are arranged at opposite ends of the rollers. Similar sets of upper and lower rollers are spaced lengthwise of the boom, as shown in FIG. 3A.

With reference to FIG. 2, the boom housing assembly 26 is attached to the rotatable apron 22 by means of a mounting plate 38 which is adapted to be bolted onto the apron, and a pair of spacer members 40 which extend between the housing and mounting plate and are welded to each. The inner end of boom 28 (to the left in FIG. 2) is connected to the puller-driver mechanism 42 through a fork bracket 44 which is bolted in place as shown (see also FIG. 6). The bracket itself is rigidly joined to boom 28 by welding. A support barrel 46, adapted to receive a retractable pin clamping head as yet to be described, is attached to the cylinder of puller-driver mechanism 42 by a coupling 47.

FIG. 6 details the connection of fork bracket 44 to cylinder 56, showing spaced ribs 45 welded inside each leg of bracket 44 to define a slot receiving the corresponding member 48 welded to cylinder 56. The members 48 are tapped to receive bolts 48.

Referring next to FIG. 3B (an enlarged view partially in section along the inner end of boom 28), the details of puller-driver mechanism 42 and the adjoining support barrel 46 are shown. The puller-driver mechanism has a cylinder 56, back and front heads 57 and '58 providing fluid connections to the cylinder at opposite ends thereof, and a piston 60. The movement of piston 60 is transmitted through piston rod 62 to a pin clamping head 64 which is slidably received within the support barrel 46. FIG. 5 shows the welded construction of barrel 46 which provides a passageway for reciprocating movement of the pin clamping head 64.

In order to make the necessary transition from the generally rectangular cross-section of cylinder 56 (to which the support barrel is connected), the circular segments 65 are extended outwardly from the rest of the box section 66 and into the circular coupling 47 The coupling includes a union nut 67 which screws on to a threaded extension 68 of cylinder front head 58. A ring groove (not shown) is provided adjacent the outer ends of the segments to receive a split ring (not shown) for cooperation with union nut 67 in the well known manner of such couplings. The opposite end of the support barrel has a flange 69 adapted to be seated against the anode side channel 14 when the boom is disposed as shown in FIG. 1.

The pin clamping head 64 (detailed in FIG. 7) has a body 70 made of non-magnetic beryllium-copper alloy, in which a threaded socket is provided for attachment of the piston rod 62. The clamping head is adapted to receive the butt portion 18 of an anode pin 16, as shown, and a pair of pin clamping dogs 76 slidably received within passageways 74 are arranged to grasp flat faces 72 of the anode pin in self-locking manner. Cover plates 78 are removable to afford access for installing the clamping dogs 76.

Piston-cylinder actuators 80 are provided for engaging and disengaging the pin clamping dogs. Each actuator has a piston 82 slidably received within the cylinder bore 84 and carrying a piston ring 83. The plunger 86 affixed to piston 82 passes through a bearing 88 to engage the adjacent pin clamping dog 76. A plug 90 seals the outer end of each cylinder 84. Fluid is introduced at either side of the piston through lateral ports such as 92. These ports in turn communicate with an internal passageway system (not shown) which extends outwardly of the body 70 for connection to suitable hose fittings at 92 (see FIG. 5).

CONTROL SYSTEM The hydraulic control system is shown schematically in FIG. 8. Conventional portions of the regular truck system include the lift cylinder 94 for raising the truck carriage 21, the tilt cylinder 96 for rotating the carriage about a horizontal axis transversely of the truck, and the lift and tilt valve 98 for controlling cylinders 94 and 96. In place of the usual hydraulic source, a pump 100 (Vickers 2621V14E8-3DD10) is used to supply both high--pressure and low-pressure fluid for purposes which are hereinafter discussed.

The high-pressure outlet 102 of the pump is connected through line 104 to inlet port 106 of valve 98. To operate the tilt control cylinder 96, a manual valve operator (not shown) is actuated to pass fluid through valve 98 from port 106 to either of ports 108 or 110, depending on which direction of movement is desired for tilt cylinder 96. Ports 108 and 110 are connected to cylinder 96 through lines 112 and 114, respectively, and as pressure is applied through one line the other is exhausted to sump in accordance with conventional construction and operation of valve 98.

The operation of lift cylinder 94 is similar, except that lifting pressure is provided by actuating a second manual valve operator to pass fluid through valve 98 from port 106 to outlet port 116, and thence to the cylinder 94 through lines 118 and 120. The opposite direction of operation, lowering the lift mechanism, is accomplished in conventional manner by using the weight of the load to force fluid out through lines 118 and 120' with port 116 exhausted to sump.

At this point it is convenient to note that the actuators 80 (used for engaging and disengaging the pin clamping dogs) are connected to a source of fluid pressure by -means of line 122 tapping into line 120. This arrangement has been found suitable due to the very low volume of fluid required for operation of these actuators. In effect, therefore, the load on lift cylinder 94 maintains a pressure in lines 120 and 122 which is adequate for this purpose, and the change of fluid volume in cylinder 94 occasioned by the requirements of actuators 80 has been found to be inconsequential for proper positioning of the lift mechanism. Fluid from line 122 is directed through control valve 124 by positioning the valve to connect line 122 either to line 125, leading to one set of operators 80 for engaging the pin clamping dogs, or to line 126 to actuate the other set of operators 80. When pressure is applied to line 125, line 126 is connected to sump, and vice versa.

Next to be considered are the control valves 130, 132 and 134 which respectively affect operation of the previously described puller-driver mechanism 42, cylinders 24 and 25 for rotating the apron 22, and the boom actuator 30. Fluid pressure is brought to these valves from the high-pressure outlet 102 of pump 100 by way of line 104 to port 106 of valve 98, as previously discussed, and from there is directed through valve 98 by positioning the manual tilt and lift operators in their neutral condition. Port 106 thereby is connected interiorly of valve 98 to an outlet leading to the T-connector 136, and thence through lines 138 and 140 to control valve 130.

To actuate the puller-driver mechanism 42, in order to extract an anode pin from the carbon anode, valve is positioned to connect supply line with line 142 leading into cylinder '56. When so positioned, valve 130 also connects the outlet line 144 into return line 146 leading back to the sump 148. With valves 132 and 134 in their neutral condition, it can be seen that communication is complete between line 146 and the sump by way of lines 150 and 152.

The operation of valves 132 and 134 is similar to that of valve 130. A first condition of valve 132 connects pressure line 146 into line 153 and through an adjustable flowcontrol valve 154 to one end of actuator 24 and the other end of companion actuator 25, while the return line 155 exits through line 150 to sump. A second condition of valve 132 does the reverse. For the boom actuator 30, pressure line 150 is connected to either of lines 156 and 157 while the other is exhausted to sump via line 152. Suitable release valves 158 are disposed at various locations as shown. All of the manual control valves 98, 124, 130, 132 and 134 are mounted on the truck 20 within convenient reach of the operator to provide remote control of the corresponding mechanisms previously discussed.

Considerable pressure up to about 1850 p.s.i. may be required in cylinder 56 to initially break loose an anode pin from the carbon anode. After the pin is freed, less pressure but considerable volume of flow is needed for suflicient travel of the piston rod 62 to retract the clamping head and pin inwardly of the support barrel. For this reason, provision is made for supplementing the flow of fluid into supply line 140 once the pressure falls below about 800 p.s.i. (or any other desired set point). This is accomplished by use of a dump valve 160 connected to the low-pressure outlet 162 of pump 100 through line 164.

Valve 160 is a type which can be biased automatically in relation to the pressure condition in supply line 140 leading to the various actuator mechanisms. This is accomplished by tapping off from valve 98 (previously de scribed) through T-connector 136 to the adjoining connector 163, and thence through line to the controller of valve 160. The valve itself is so constructed that its inlet line 164 is connected interiorly of the valve either to the outlet line 166 leading to the sump 148, or to the outlet line 168. In the latter condition, fluid from the lowpressure side of the pump passes outwardly through line 168, check valve and line 172 to a T-connector 174, where the fluid enters the supply line between sections 138 and 140.

Which of the two possible outlet conditions will exist is controlled as follows. If the sensed pressure brought into valve 160 through line 165 is greater than a pre-set criterion (typically about 800 p.s.i.), line 164 from the pump is connected to outlet line 166 and to sump. In this situation there is no load on the low-pressure side of the pump. On the other hand, if the sensed pressure is below about 800 p.s.i., line 164 is connected to outlet line 168, and a supplemental supply of low-pressure fluid is directed from line 168 through check valve 170, line 172 and line 140, to furnish an additional volume of fluid. In this manner, high-pressure fluid is available for initial heavy load conditions, and increased flow rates are available for low-pressure requirements after the load decreases.

SUMMARY OF OPERATIONS The steps involved in a complete cycle of pulling and resetting an anode pin may be summarized as follows:

After truck 20 is positioned alongside the pot 10, the operator extends boom 28 toward the pot (using control valve 134 to actuate cylinder 30). In order to align the boom wtih the pin 16 to be removed, it may also be necessary to rotate the boom and revolving apron 22 (controlled by operation of valve 132); and should the pin have become skewed, so that the parallel flat faces 72 of the pin butt portion 18 are not disposed vertically, the tilt mechanism 96 is actuated by operating valve 98 to align the pin clamping head 64 with the pin in this regard.

The boom is extended toward pot until flange 69 of the support barrel 46 is seated against the anode side channel 14, with pin 16 extending into the pin clamping head 64. Then the pin clamping dogs are engaged With butt portion 18 of the pin, using valve 124 to actuate the pin-engaging set of operators 80, and the clamping head 64 is retracted within the support barrel 46 to release the pin from the carbon anode 12. This retraction is accomplished by the puller-driver mechanism 42, under the control of valve 130, and it is to be noted particularly that pressure applied to piston 60 (through line 142 leading from valve 130) causes an opposite and substantially equal reaction force on front head 58 of cylinder 56, which is transmitted through the coupling 47 to support barrel 46, and is directed against the anode side channel 14 by means of flange 69 at the adjacent end of the support barrel.

The clamping head and pin having been moved outwardly from the anode, the entire boom assembly is retracted toward the truck (by positioning valve 134 to operate boom cylinder 30) and apron 22 is rotated (counterclockwise in FIG. 1) to the extent necessary for the protruding end of the pin to clear the pot superstructure. Then the truck carriage 21 and attached boom mechanism are raised vertically, by operating lift valve 98 to actuate 6 cylinder 94, in preparation for inserting the pin at a higher level (see phantom outline in FIG. 1).

To align the boom in pin-driving condition, the operator rotates truck apron 22 in the opposite direction (clockwise) to orient pin 16 at the desired angle for passage through a clearance hole in'the anode side channel, and extends boom 28 toward the pot until the pin is started into the anode 12. Then the pin clamping head is advanced by actuating puller-driver mechanism 42 to drive the pin into place, and the pin clamping dogs are disengaged from the pin.

While the presently preferred embodiment of the invention and its method of operation have been illustrated and described, it will be apparent that the invention may be otherwise variously embodied and practiced within the scope of the following claim.

What is claimed is:

1. The method of manipulating anode pins relative to a self-baking carbon anode of an electrolytic reduction cell, said anode being adjustable to compensate for consumption of carbon during operation of the cell and having a plurality of anode pins providing electrical connection to the anode, the pins having to be removed periodically as they are advanced with the anode toward the molten contents of the cell, which method comprises:

extracting an anode pin from a baked region of the carbon anode in which the pin is securely anchored, by pulling the pin outwardly from said anode while reacting an opposing force inwardly against the anode to compensate substantially for the pulling efiort; and

promptly reinserting said pin while still hot into a softer and substantially unbaked region of said anode away from the molten contents of the cell.

References Cited FOREIGN PATENTS 140,584 2/1961 U.S.S.R. 204-243 1,110,882 11/1955 Germany 20467 JOHN H. MACK, Primary Examiner D. R. VALENTINE, Assistant Examiner 

